1. Field of the Invention
The present invention relates to pressure testing devices, and more particularly, to a pressure testing device capable of producing stable positive and negative pressure sources and testing the pressure state of an object.
2. Description of Related Art
Currently, a variety of electronic products have a waterproof or moisture-proof function, such as waterproof digital watches, waterproof mobile phones, waterproof digital cameras and so on, and more and more electronic products are desired to have a waterproof or moisture-proof function.
Generally, a waterproof or moisture-proof test is performed to an object by disposing the object in water or applying an air pressure on junctions between components of the object, wherein the air pressure is used to simulate a water pressure. For example, a negative pressure or a positive pressure can be applied on the junctions and a pressure sensor can be used to sense the pressure that is maintained by the object. Once the object cannot maintain a certain degree of pressure, it represents that the object is leaking air and has poor waterproof or moisture-proof performance.
To perform the above-described test method, devices for producing negative and positive pressures are required. Generally, a vacuum pump is necessary for producing a negative pressure and an air compressor is necessary for producing a positive pressure. However, the use of the two types of devices is costly and space-consuming. Therefore, it is desirable to develop a simplified testing device capable of producing both positive and negative pressures.
Further, the accuracy of air pressure produced by the air compressor is lower than the vacuum pump. Therefore, in a conventional positive pressure test, it is quite difficult to accurately regulate the positive pressure applied on an object under test.